The present invention relates to a new and improved construction of operating apparatus for an electronic musical instrument provided with at least one synthesizer.
Generally speaking, this operating apparatus comprises a wind or blowing body constructed and playable similar to a mouth-harmonica and in which there are arranged elements responsive to the blowing and suction air current or stream of a human operator and to the location where such occurs. These elements control the synthesizer as a function of their response.
An operating apparatus of this general type has become known to the art, for instance, from German Patent Publication No. 1,772,103 published Apr. 8, 1971, wherein there is described an electronic mouth-harmonica. As with a conventional mouth-harmonica, the wind or blowing body of this prior art operating apparatus is provided with a row of wind or blow-holes, from each of which there outbounds a flow channel. Operatively associated with each of these flow channels is an element which has a piston or bellows-like configuration and responds with a mechanical motion to negative pressure, i.e. suction, and excess pressure, i.e. blowing. Each of these elements cooperates with a resilient lamella or small plate such that upon response of the related element the lamella is lifted and together therewith there equally is lifted-off a contact rail which extends over all lamellae and in its rest position contacts all of the lamellae. With a lamella lifted, there thus exists an electrical contact only between this lifted lamella and the contact rail. Each lamella is electrically connected to the junction or node between two successively arranged resistors of a large number of resistors which are connected in series. These series-connected resistors form a circuit element which determines the frequency of an oscillator incorporated into the wind or blowing body itself. Depending upon which lamella is lifted by suction or blowing, there can be altered the resistance value of the series circuit, and thus, the frequency of the electrical oscillations generated by the oscillator.
Furthermore, this prior art operating apparatus also is provided with a light barrier containing a photoresistor forming a receiver. According to the amount by which the aforementioned contact rail is lifted, this light barrier is interrupted to a greater or lesser extent. By altering the resistance value of the photoresistor there is correspondingly altered the amplitude of the electrical oscillations generated by the oscillator. With this state-of-the-art apparatus, the thus generated electrical oscillations are further converted or transformed, for instance by superimposing thereon overtones or harmonics or by subjecting them to frequency division and amplification, and thereafter, these modified electrical oscillations are delivered to an electro-acoustic converter. This electro-acoustic converter transforms the received periodic electrical signal into an appropriate acoustical sound.
This prior art operating apparatus is afflicted with various and, in part, considerable disadvantages, of which only a few will be described hereinafter. Since each of the flow-channels outbounding from the wind or blow-holes is operatively associated with a mechanically movable element responding to excess pressure, i.e. blowing, or negative pressure, i.e. suction or sucking, it is practically impossible that all these elements react to the same degree to an excess pressure or negative pressure which is predetermined with respect to its value. As a consequence, the loudness level or intensity of the sound which is audible from the electro-acoustic converter can vary from blow-hole to blow-hole, even with a constant value of the excess pressure or negative pressure. Moreover, the mechanically movable elements, responsive to excess pressure and negative pressure, are fully exposed to the human suction or blowing air current or stream. However, especially the blowing air stream of a human is everything else but purely clean dry air. Therefore, the mobility of these elements is considerably impaired even after a short period of use of such prior art apparatus, which also affects the operation, especially that of the electrical part of the apparatus.
Furthermore, the resistance values of the resistors of the afore-mentioned series circuit are temperature-dependent, so that the frequency of the electrical oscillations generated by the oscillator, and together therewith the pitch of the sound generated by the converter, fluctuate, even if to a lesser extent, as a function of the ambient temperature and the temperature of the apparatus, respectively.
Since, with the known operating apparatus there are present a large number of movable elements which, at least theoretically, should react or move even under the influence of very small forces, i.e. slight blowing or suction pressure, the prior art apparatus, during playing, equally reacts in a very sensitive manner to shocks and/or vibrations which act upon the wind or blowing body. Therefore, the musician, during playing, has to be very conscious that he or she does not impart any sudden movements or accelerations to the wind or blowing body.
Other exemplary constructions of the prior art are typified by the disclosures of U.S. Pat. No. 3,143,027 and German Patent Publication No. 2,338,513.